Influence of powdered dentin on the shear bond strength of dentin bonding systems

This study evaluated the effect of different amounts of dentin powder (DP) mixed in Clearfil SE Bond (CSB) or Single Bond (SB) on adhesion to dentin. Human third molars (n=96) were sectioned to expose the mid-coronal dentin and divided into eight experimental groups (n=12 per group), namely, Group 1: CSB, Group 2: CSB+1.5 mg DP, Group 3: CSB+3 mg DP, Group 4: CSB+4.5 mg DP, Group 5: SB, Group 6: SB+1.5 mg DP, Group 7: SB+3 mg DP, and Group 8: SB+4.5 mg DP. Filtek Z250 composite was bonded onto dentin, and all specimens were subjected to shear bond strength test at a crosshead speed of 1 mm/min. Highest bond strength was obtained in Groups 1, 2, and 3 (15.1, 13.5, and 16.4 MPa respectively; p>0.05) and the lowest in Groups 6, 7, and 8 (5.5, 5.6, 4 MPa; p>0.05). DP addition, regardless of amount, adversely affected the bond strength of SB. Bond strength of CSB was not affected when 1.5 or 3 mg of DP was added.